LPS-34571 Provide a list of common services in the template editor palette

I'm leaving the help texts empty for now and have asked the documentation team to fill it in.
LPS-34571 I made the following changes:

1.) WikiPortletDisplayTemplateHandler and another still called it "assetTagsServicesTemplateVariableGroup", I just renamed it to the approrpatie one. Cut and paste error.

2.) Sometimes, you declared the service classes alphabetically (local before remote), and sometimes, not alphabetically. I made them all alphabetical.

3.) I changed templateVariableGroup#addServiceLocatorVariable to take in a list of classes. It makes the usage of this class much cleaner. Less stuff to sift through (mentally).

4.) templateVariableGroups.put("xxx" is now templateVariableGroups.put(templateVariableGroup.getLable()). I saw they were always the same and wanted to remove the code duplication.
LPS-34571 Remove empty language keys for now. Doc team can readd manually, OR.. even better. Jorge, we should auto fill this via JavadocManagerUtil. Right now, in localhost:8080/api we auto fill the JSON apis with text from the Javadocs. But it only does it at the method level and not the class level. I'm going to ask Igor to expose this, so that the Javadoc team only has to document the class, and it'll automatically fill in.
LPS-34571 Remove bad key
LPS-34571 Lang keys